Excess Risk for Venous Thromboembolism Persists for Months After COVID-19

People with severe COVID-19 are at excess risk for venous thromboembolism (VTE), but whether risk also rises among patients with mild disease is unclear. Using Swedish national health databases, researchers identified more than 1 million people who tested positive for SARS-CoV-2 between February 2020 and May 2021; incidence of first deep venous thrombosis (DVT), pulmonary embolism (PE), and bleeding during the subsequent 180 days was recorded. Controls were a matched cohort of 4 million people who did not have COVID-19.

After adjustment, risks for DVT, PE, and bleeding were significantly higher in the 30 days after diagnosis of COVID-19 compared with no COVID-19 diagnosis (risk ratios: 5, 33, and 2, respectively), and these risks remained significantly elevated for 3, 6, and 2 months, respectively. Risk ratios were elevated primarily in patients who were hospitalized for COVID-19; for patients who were not hospitalized, risks were lower (RRs: 3, 7, and 1, respectively). Absolute risks for all these events were low (e.g., 0.17% for PE in the first 30 days after COVID-19 diagnosis vs. 0.004% for controls).